We look at the evolution of plant physiology in terrestrial plants. An expanding knowledge of phylogenetic relationships between living species allows us to explore how key functions of plants have changed over millenia. Our focus is mainly on the tubes (xylem) and valves (stomata) that make leaves work.
Tiny valves called stomata regulate leaf water use. Consequently, stomata also regulate terrestrial productivity and water cycling. The evolution and function of these valves thus has a giant impact globally.
Water is the main limit to photosynthesis on land, and plants use a network of xylem veins supply water to irrigate leaves. More veins means more water and hence more photosynthesis, but veins are costly to make, so plants seem to coordinate vein production with photosynthetic potential.
Throughout history plant taxa have moved or disappeared during episodes of climate change. We explore the physiology behind species sensitivity to rainfall and temperature.